The present invention relates to a novel lifting device for raising a load onto the roof of a building utilizing a ladder.
Many items of material and equipment must be lifted onto the roof portion of a building. For example, roof tiles, air conditioning units, fans, and the like are normally placed on the top surface of the roof of a building. In the past, lifting devices such as cranes, cherry pickers, helicopters, and the like have been employed to accomplish this task. Although successful in lifting such loads, these items of equipment require multiple persons and are quite expensive to operate.
Several systems have been proposed for use with ladders for the purpose of lifting loads onto a roof. For example, U.S. Pat. No. 5,275,256 depicts a ladder carriage apparatus in which a pair of floor plates are connected to a side plate that is lifted up and down the ladder by a pulley.
U.S. Pat. Nos. 3,666,054, 4,183,423, and 4,546,853 show dollies or sleds that are lifted up the side rungs of a ladder by using a pulley system. Presumptively, when the load reaches the top of the ladder someone on the roof is required to lift the load from the platform to bring it onto the roof. The systems depicted in these patents normally would require at least two persons to move loads up and down a ladder onto a roof of a building.
A load lifting system used in conjunction with the ladder to move the load to the roof of a building that can be operated by a single person would be a notable advance in the art of materials transportation.